Flexible tube for cartridge filter

ABSTRACT

Embolic protection filtering devices and methods of making and using the same. The present invention may include an embolic protection filtering device including a filter cartridge that is slidable over medical devices, for example, guidewires. The filter cartridge may have a filter coupled thereto and may have desirable flexibility and trackability characteristics.

This application is a continuation application of U.S. application Ser.No. 10/373,482, as filed on Feb. 24, 2003, now U.S. Pat. No. 6,828,291.

FIELD OF THE INVENTION

The present invention pertains to embolic protection filters. Moreparticularly, the present invention pertains to filters coupled to ashaft having desirable flexibility and trackability characteristics.

BACKGROUND

Heart and vascular disease are major problems in the United States andthroughout the world. Conditions such as atherosclerosis result in bloodvessels becoming blocked or narrowed. This blockage can result in lackof oxygenation of the heart, which has significant consequences sincethe heart muscle must be well oxygenated in order to maintain its bloodpumping action.

Occluded, stenotic, or narrowed blood vessels may be treated with anumber of relatively non-invasive medical procedures includingpercutaneous transluminal angioplasty (PTA), percutaneous transluminalcoronary angioplasty (PTCA), and atherectomy. Angioplasty techniquestypically involve the use of a balloon catheter. The balloon catheter isadvanced over a guidewire such that the balloon is positioned adjacent astenotic lesion. The balloon is then inflated and the restriction of thevessel is opened. During an atherectomy procedure, the stenotic lesionmay be mechanically cut away from the blood vessel wall using anatherectomy catheter.

During angioplasty and atherectomy procedures, embolic debris can beseparated from the wall of the blood vessel. If this debris enters thecirculatory system, it could block other vascular regions including theneural and pulmonary vasculature. During angioplasty procedures,stenotic debris may also break loose due to manipulation of the bloodvessel. Because of this debris, a number of devices, termed embolicprotection devices, have been developed to filter out this debris.

BRIEF SUMMARY

The present invention pertains to embolic protection filtering devices.In at least some embodiments, the filtering device may include a filtercartridge having a filter coupled thereto. The filter cartridge may beconfigured to be slidable over a medical device, for example aguidewire, and may have desirable flexibility, trackability, and otherfeatures and/or characteristics as described in more detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an example embolic protection filteringdevice;

FIG. 2 is a perspective view of another example filter cartridge;

FIG. 3 is a perspective view of another example filter cartridge;

FIG. 4 is a perspective view of another example filter cartridge;

FIG. 5 is a perspective view of another example filter cartridge;

FIG. 6 is a perspective view of an example mandrel;

FIG. 7 is a cross-sectional view taken through line 7-7;

FIG. 8 is an alternative cross-sectional view taken through line 7-7;and

FIG. 9 is a perspective view of another example mandrel.

DETAILED DESCRIPTION

The following description should be read with reference to the drawingswherein like reference numerals indicate like elements throughout theseveral views. The detailed description and drawings illustrate exampleembodiments of the claimed invention.

FIG. 1 illustrates an example embolic protection filtering device 10.Device 10 may include a tubular filter cartridge 12 having a filter 14coupled thereto. Filter cartridge 12 may have desirable flexibility,trackability, and/or other characteristics that allow it to be exchangedover other medical devices such as a guidewire 16 (as shown in FIG. 1),a catheter, and the like. Moreover, because a number of the features andcharacteristics of filter cartridge 12 can be varied, cartridge 12 canbe configured to be slidable over essentially any medical device,including virtually all commercially available guidewires and catheters.

Filter cartridge 12 may be comprised of a number of different materialsincluding metals, metal alloys, polymers, or the like, or combinationsor mixtures thereof. For example, filter cartridge 12 may be comprisedof super elastic, linear elastic, and/or shape memory metals and/ormetal alloys. Some examples of suitable metals and metal alloys includestainless steel, such as 304v stainless steel; such as nickel-titaniumalloy, such as nitinol, nickel-chromium alloy, nickel-chromium-ironalloy, cobalt alloy, titanium and/or titanium alloys, or the like; orother suitable material.

Some examples of suitable polymers may include polytetrafluoroethylene(PTFE), ethylene tetrafluoroethylene (ETFE), fluorinated ethylenepropylene (FEP), polyurethane, polypropylene (PP), polyvinylchloride(PVC), polyether-ester (for example a polyether-ester elastomer such asARNITEL® available from DSM Engineering Plastics), polyester (forexample a polyester elastomer such as HYTREL® available from DuPont),polyamide (for example, DURETHAN® available from Bayer or CRISTAMID®available from Elf Atochem), elastomeric polyamides, blockpolyamide/ethers, polyether block amide (PEBA, for example availableunder the trade name PEBAX®), silicones, polyethylene, Marlexhigh-density polyethylene, Marlex low-density polyethylene, linear lowdensity polyethylene (for example REXELL®), polyethylene terephthalate(PET), polyetheretherketone (PEEK), polyimide (PI), polyetherimide(PEI), polyphenylene sulfide (PPS), polyphenylene oxide (PPO),polysulfone, nylon, perfluoro(propyl vinyl ether) (PFA), other suitablematerials, or mixtures, combinations, or copolymers thereof. In someembodiments filter cartridge 12 can include a liquid crystal polymer(LCP) blended with other polymers to enhance torqueability. By employingselection of materials and processing techniques, thermoplastic, solventsoluble, and thermosetting variants of these and other materials can beemployed to achieve the desired results.

In some embodiments, a coating, for example a lubricious, a hydrophilic,a protective, or other type of coating may be applied over portions orall of filter cartridge 12, or other portions of device 10. Hydrophobiccoatings such as fluoropolymers provide a dry lubricity which improvesguidewire handling and device exchanges. Lubricious coatings improvesteerability and improve lesion crossing capability. Suitable lubriciouspolymers are well known in the art and may include silicone and thelike, hydrophilic polymers such as polyarylene oxides,polyvinylpyrolidones, polyvinylalcohols, hydroxy alkyl cellulosics,algins, saccharides, caprolactones, and the like, and mixtures andcombinations thereof. Hydrophilic polymers may be blended amongthemselves or with formulated amounts of water insoluble compounds(including some polymers) to yield coatings with suitable lubricity,bonding, and solubility.

In some embodiments, filter cartridge 12 or portions thereof may bedoped with, plated with, or otherwise include a radiopaque material.Radiopaque materials are understood to be materials capable of producinga relatively bright image on a fluoroscopy screen or another imagingtechnique during a medical procedure. This relatively bright image aidsthe user of device 10 in determining its location. Some examples ofradiopaque materials can include, but are not limited to, gold,platinum, palladium, tantalum, tungsten alloy, plastic material loadedwith a radiopaque filler, and the like.

The choice for material composition may help provide filter cartridge 12with a number of desirable characteristics. For example, materialcomposition may provide filter cartridge 12 with desirablecharacteristics related to strength, flexibility, trackability,ovalization avoidance, coefficient of friction, axial compression, andthe like. In addition or as an alternative to material composition,filter cartridge 12 may vary in other ways to provide filter cartridge12 with desirable features and characteristics including those listedabove. For example, the flexibility of filter cartridge 12 may varyalong its length. This feature can be accomplished in a number ofdifferent manners, including changing the material composition oraltering the inside and/or outside diameters of filter cartridge 12.Additionally, filter cartridge 12 may be comprised of multiple layers ofmaterials and/or multiple sections or regions that are coupled.

In at least some embodiments, filter cartridge 12 may also include oneor more notches 17 or other structural features that may, for example,provide filter cartridge 12 with desirable characteristics includingthose listed above. For example, FIG. 1 depicts the one or more notches17 as defining a helical groove 19 formed in filter cartridge 12.Helical groove 19 can be formed in a number of ways. For example, groove19 can be cut into filter cartridge 12 using known laser or other typeof cutting or etching process. A number of other processes can beutilized to form groove 19. For example, filter cartridge 12 can bemolded (e.g., injection molded, etc.) in a manner that defines groove19. Alternatively, filter cartridge 12 may be comprised of a flattenedribbon that is wound into a shape that defines a tubular filtercartridge 12 having groove 19. It can be appreciated that groove 19 maybe defined in a number of additional ways without departing from thespirit of the invention.

The shape, arrangement, and configuration of groove 19 may also vary.For example, groove 19 is illustrated in FIG. 1 as being an essentiallyregular helix extending along the length of cartridge 12. In someembodiments, however, groove 19 may vary. For example, groove 19 mayextend along only portions of cartridge 12 or intermittently alongsections of cartridge 12. Additionally, the pitch of groove 19 may vary.For example, the pitch of groove 19 may be relatively wide or open atsome positions (e.g., near the proximal region of cartridge 12) andrelatively close at others (e.g., near the distal region of cartridge12). Moreover, the direction of groove 19 may vary. For example, groove19 may wind about cartridge 12 in a clockwise direction,counterclockwise direction, or combinations of directions.

It can be appreciated that groove 19 in filter cartridge 12 may providedevice 10 with a number of desirable features. For example, groove 19may increase the flexibility of cartridge 12. Additionally, groove 19may increase the trackability of cartridge 12. Trackability isunderstood to be the ability of one device (e.g., cartridge 12) to“track” or advance over another (e.g., guidewire 16). According to thisembodiment, groove 19 may increase trackability, for example, by makingcartridge 12 more adaptable or more compliant so that it may more easilytrack over a device (i.e., guidewire 16) that may be significantlycontorted when positioned in the tortuous vasculature.

As stated above, some of the other components of device 10 may includefilter 14. Filter 14 may be adapted to operate between a first generallycollapsed configuration and a second generally expanded configurationfor collecting debris in a body lumen. In some embodiments, filter 14can be delivered to an appropriate intravascular location, for example“downstream” of an intravascular lesion, using an appropriate filterdelivery and/or retrieval device 18. Similarly, filter 12 can be removedfrom the vasculature at the desired time with device 18 or anothersuitable device.

Filter 14 may include a filter frame 20 and a filter membrane or fabric22 coupled to filter frame 20. Frame 20 may take the form of any one ofa number of appropriate shapes and configurations. For example, frame 20may comprise a generally circular filter mouth or loop, which maydefines the primary opening for blood to travel into and be filtered byfilter 14. However, essentially any appropriate shape or configurationmay be utilized without departing from the spirit of the invention.

Frame 20 may be comprised of any appropriate material. For example,frame 20 may be comprised of a “self-expanding” shape-memory materialsuch as nickel-titanium alloy (to bias filter 14 to be in the secondexpanded configuration). Alternatively, frame 20 may be comprised ofessentially any appropriate metal, metal-alloy, polymer, combinationsthereof, and the like including any of the materials described herein.

Filter membrane 22 may be comprised of any appropriate material such asa polymer and may be drilled (for example, formed by known lasertechniques) or otherwise include at least one opening 24. Holes oropenings 24 can be sized to allow blood flow therethrough but restrictflow of debris or emboli floating in the body lumen or cavity.

One or more struts 26 may extend between frame 20 and filter cartridge12. In some embodiments, struts 26 can be coupled to filter cartridge 12by a coupling 28, for example a heat-shrink tube, a crimp fitting, andthe like. Alternatively, struts 26 may be coupled to filter cartridge 12by one or more windings of struts 26 about filter cartridge 12.

As stated above, at least some embodiments of device 10 includeguidewire 16, over which filter cartridge 12 may be slidably disposed.Guidewire 16 may include a distal stop 30. Distal stop 30 may define adistal-most position along guidewire 16 may be advanced to. In addition,guidewire 16 may also include a proximal stop 32. Stops 30/32 may bearranged so that filter cartridge 12 can be positioned between them. Adeployment sheath 34 may also be slidably disposed over guidewire 16.Sheath 34 may be used, for example, to help advance filter cartridge 12to the appropriate location along guidewire 16.

Although FIG. 1 illustrates filter cartridge 12 being slidably disposedover guidewire 16, the invention is not intended to be limited to usewith only guidewires 16. It can be appreciated that the device could beany intravascular device or be any device designed to pass through anopening or body lumen. For example, the device may comprise a catheter(e.g., therapeutic, diagnostic, or guide catheter), endoscopic device,laproscopic device, an embolic protection device, or any other suitabledevice.

The use of filter cartridge 12 may include a number of steps. Forexample, filter cartridge 12 may be coupled to guidewire 16, for exampleby disposing cartridge between stops 30/32, by crimping cartridge 12onto guidewire 16, by using other suitable mechanical connections, or byany other suitable means. In some embodiments, cartridge 12 andguidewire 16 may be coupled before guidewire 16 is advanced through ablood vessel. Alternatively, guidewire 16 may be positioned in a bloodvessel and then cartridge 12 may be advanced over guidewire 16 to asuitable target location and filter 14 may be expanded. Advancingcartridge 12 over guidewire 16 may include the use of delivery sheath 18and the expansion of filter 14 may include advancing deployment sheath34 into contact or another suitable arrangement to expand filter 14.Sheath 18 and/or sheath 34 may be proximally retracted and anotherdiagnostic or therapeutic device (e.g., balloon catheter, atherectomycatheter, and the like) may be advanced over guidewire 16. The expandedfilter 14 may then be used to filter debris that may be generated by thetherapeutic device.

FIG. 2 is a perspective view of another example filter cartridge 112.Cartridge 112 is similar to cartridge 12, expect that the one or morenotches 117 define a plurality of slots 119 within cartridge 112. Slots119 may be formed according to any of the methods described herein orany other appropriate process. The shape, arrangement, and number ofslots 119 may vary without departing from the spirit of the invention.For example, slots 119 may be generally rectangular in shape, square inshape, rounded in shape, or have any other appropriate shape.Additionally, slots 119 may be disposed at varying positions alongcartridge 112 and may vary in length so as to span, for example, about45 to about 320 degrees around the circumference of cartridge 112 ormore or less, depending the desired length. In some embodiments, abridge or other tying support (not shown) may be longitudinally disposedalong cartridge 112, for example along the inside surface, to helpmaintain the structural integrity of cartridge 112. This structuralfeature may be desirable when slots 119 span larger portions ofcartridge 112. Other variations for the configurations and arrangementsof slots 119 may include any of the variations attributed to any of thenotches and/or cartridges described herein.

FIG. 3 is a perspective view of another example filter cartridge 212.Cartridge 212 is similar to the other cartridges disclosed herein,expect that it includes a series of fibers arranged in a braid 236.Braid 236 may be adapted and configured to provide cartridge 212 withdesirable flexibility and trackability characteristics including thosedescribed above. In some embodiments, braid 236 may be disposed on theoutside surface (as shown in FIG. 3) or the inside surface (not shown)of a support structure or tube 238. Alternatively, cartridge 212 may becomprised of braid 236 without the need for support tube 238. Accordingto this embodiment, cartridge may be manufactured, for example, bydisposing braid 236 on a mold or mandrel to define cartridge 212, andthen disassociating the defined filter cartridge 212 from the mold.

The arrangement and configuration of braid 236 may vary. For example,braid 236 may have a uniform or regular distribution along cartridge212. Alternatively, the pattern may be irregular or intermittent. Thedirection, closeness or tightness, and general shape may also vary.Moreover, additional braids or layers may be disposed on braid 236. Forexample, cartridge 212 may include a plurality of braids 236 disposed oneach other and may include other, non-braided layers disposedtherebetween.

FIG. 4 is a perspective view of another example filter cartridge 312.Cartridge 312 is similar to other cartridges disclosed herein, exceptthat it includes a coil 340. It can be appreciated that coil 340 mayprovide cartridge 312 with desirable flexibility characteristics. Forexample, including coil 340 or a similar coiled structure may increasethe flexibility of cartridge 312. Additionally, coil 340 may enhance thetrackability of filter cartridge 312. In some embodiments, coil 340 maycomprise cartridge 312 thereby obviating the need for any support tubeor structure. Other embodiments, however, may include a supportstructure similar to support tube 238 illustrated in FIG. 3.

FIG. 5 is a perspective view of another example filter cartridge 412.Cartridge 412 is similar to cartridge 312, except that a portion of coil440 is “unwound” or otherwise configured to define filter frame 420 offilter 414. According to this embodiment, cartridge 412 and filter frame420 may be integral with one another or otherwise formed of the samestructure. This structural feature may be desirable for a number ofreasons. For example, cartridge 412 may cost less to manufacture bydecreasing the number of separate structural elements and by decreasingsome of the processing steps (e.g., attaching together separateelements).

FIG. 6 is an example mold or mandrel 542 that may be used in themanufacturing of filter cartridges, including those described herein andother embodiments. Mandrel 542 may include a base or base surface 544and may include one or more projections 546 extending therefrom. Mandrel542 may be comprised of any appropriate material, including thosedisclosed herein. In some embodiments, mandrel 542 may be comprised of awax or other soluble substance that can be readily dissolved followingthe molding procedure. This feature may be desirable by enhancing theability to release a newly molded filter cartridge from mandrel 542.

The shape, size, and arrangement of projections 546 may also vary. Insome embodiments, a plurality of rounded projections 546 may beessentially uniformly distributed throughout mandrel 542. Alternatively,projections 546 may have a square or other shape and may be irregularlydistributed. Additionally, a variety of shapes, sizes, and distributionsmay be utilized along mandrel 542.

Molding of a filter cartridge with mandrel 542 may include any of anumber of known molding techniques. For example, manufacturing mayinclude dip molding, spray molding, injection molding, and the like.These manufacturing techniques may generally include disposing a filtercartridge material (not shown) adjacent mandrel 542 so as to define afilter cartridge. The newly defined cartridge may be disassociated frommandrel 542 and the flexibility thereof may be altered. For example, theflexibility may be altered by forming one or more notches or slotstherein, by forming a spiral groove therein, etc. as described above.Other manufacturing steps may include coupling a filter, for examplefilter 14, to the newly molded filter cartridge.

FIGS. 7 sectional and 8 illustrate cross-sectional views of mandrel 542where example filter cartridges have been molded thereon. For example,FIG. 7 illustrates filter cartridge 512 molded on mandrel 542. Accordingto this embodiment, the shape of cartridge 512 may include a pluralityof projections 548 a/b along both its inside surface 550 and its outsidesurface 552, respectively, that generally conform to the shape ofmandrel 542. In some other embodiments, an alternative filter cartridge612 may be molded as shown in FIG. 8. Cartridge 612 may be configured orotherwise thickened so that projections are 648 a may be seen on insidesurface 650, but not on outside surface 652.

Another example mandrel 742 is illustrated in FIG. 9. Mandrel 742 isessentially the same in form and function as mandrel 542, except that itincludes one or more dimples 746 extending inward from a base member744. Mandrel 742 may be used to mold filter cartridges in a mannersimilar to what is described above. For example, molding a filtercartridge using mandrel 742 may result in a filter cartridge withdimples similar to dimples 746.

It should be understood that this disclosure is, in many respects, onlyillustrative. Changes may be made in details, particularly in matters ofshape, size, and arrangement of steps without exceeding the scope of theinvention. The invention's scope is, of course, defined in the languagein which the appended claims are expressed.

1. A filter assembly, comprising: a filter cartridge having a first end,a second end, an intermediate portion therebetween, and a lumenextending therethrough and adapted to receive an elongate shaft, whereinthe filter cartridge includes a braid defining, in part, an undulatingouter surface of the filter cartridge; a filter frame fixedly attachedto an outer surface of the intermediate portion of the filter cartridge;and a filter membrane for trapping emboli attached to the filter frame.2. The filter assembly of claim 1, wherein the first end and the secondend of the filter cartridge define the longitudinal extents of thefilter assembly.
 3. The filter assembly of claim 1, wherein the filtercartridge is concentrically attached to the filter frame.
 4. The filterassembly of claim 1, wherein the filter cartridge is eccentricallyattached to the filter frame.
 5. The filter assembly of claim 1, whereinthe filter cartridge extends through the filter frame.
 6. The filterassembly of claim 1, wherein the filter cartridge comprises a tubularmember extending from the first end to the second end, and wherein thefirst end and the second end of the filter cartridge define thelongitudinal extents of the filter assembly.
 7. An embolic protectiondevice, comprising: an elongate guidewire; a tubular filter cartridgeslidably disposed over the guidewire, the filter cartridge including abraided member defining at least a portion of an undulating outersurface of the filter cartridge; and an embolic protection filtercomprising a filter membrane or fabric, the filter permanently attachedto an outer surface of an intermediate portion of the filter cartridge.8. The embolic protection device of claim 7, wherein the guidewireincludes one or more stops coupled thereto.
 9. A medical device,comprising: an elongate shaft having a proximal region and a distalregion; and a filtering apparatus disposed at least partially on theelongate shaft, the filtering apparatus including a tube having a firstend, a second end, and a helical groove formed therein, a filtercomprising a filter membrane or fabric and disposed about the helicalgroove, a first stop configured to abut the tube in a first position anda second stop configured to abut the tube in a second position, whereinthe filter in the second position is more distal relative to the filterin the first position.
 10. The device of claim 9 wherein the grooveextends along only a portion of the shaft.
 11. The device of claim 9wherein the groove extends intermittently along the shaft.
 12. Thedevice of claim 9 wherein the groove is formed by cutting the tube. 13.The device of claim 9 wherein the tube is metallic.
 14. The device ofclaim 9 wherein the tube includes a nickel-titanium alloy.
 15. A medicaldevice, comprising: an elongate shaft having a proximal region and adistal region; a tube slidably disposed about the distal region of theelongate shaft, the tube having a helical groove formed therein; afilter comprising a filter membrane or fabric and disposed over thehelical groove and slidably disposed on the shaft.
 16. The device ofclaim 15 wherein the groove extends along only a portion of the tube.